Wasps which have killed six and injured hundreds since August are to meet their Waterloo.

The local government in Ankang, a city in Northwest China's Shaanxi Province, now says the time has come to stamp out the deadly insect menace.

"It is the right time to kill the killers as the weather gets cold. The local government has set up special working groups and sent them to the places where the wasps are concentrated," said Wang Anli, secretary-general of the Ankang municipal government.

As temperatures dip, the killer insects are going into hibernation. Experts say the less active wasps are easier to kill.

So far, firefighters have carried the burden of dealing with the deadly insects in Ankang's Hanbin District, where the threat has been particularly fierce, the secretary-general said.

"We will expand our wasp extermination drive gradually," Wang said.

However, the insects cannot be eliminated completely, because many nests are hard to find and hard to reach, said Cheng Yingwen, an official from the Ankang Forestry Bureau.

"The insects' nests can be as high as 30 metres up in trees, which makes them hard to tackle," Cheng said.

At 3 centimetres long, the wasps are giants of their kind and have a sting capable of killing inside 24 hours, experts said.

On August 18, an 11-year-old girl named Wang Fang was attacked in Ankang's Pingli County as she played in her backyard.

The next day the girl was dead even though she received prompt medical treatment, said Zhang Xiaojun, a doctor at Ankang Central Hospital.

Zhang said his hospital had received an increasing number of sting victims in recent years.

"In 2002, we treated 10 patients for wasp stings and six died. In 2003, six out of 18 wasp-sting patients died. Last year the death toll was nine out of 20."

According to hospital statistics, by November 11 this year it had treated 43 patients stung by the wasps. Six had died, and another six are still being treated.

"Over the past four years, the insects have killed some 30 people and injured 300 in Ankang," Zhang added.

There have been reports of killer wasps attacking people in other areas of the country, including in rural areas around Xi'an, capital of Shaanxi Province.

Hua Baozhen, an insect expert and professor at the Northwest Agriculture and Forestry Science University, thinks the problem is due to changes in the environment.

"The wasps have been around for a long time and rarely attacked people before now," Hua said.

The overuse of pesticides killed many insects, affecting the natural balance and allowing wasp numbers to grow. Thus the killers have more and more come into conflict with humans.

(China Daily November 15, 2005)